“Not a chance in hell,” I said quietly, and not entirely metaphorically. “I’m pretty sure I couldn’t call up this much energy in the first place. And even if I could, I wouldn’t have anything left to control it with.” I closed my eyes for a moment, trying to feel any lingering traces of power around the area, but the destruction and subsequent drift of dust and snow and smoke had obscured any coherent patterns that might have given me hints about how the working had been accomplished.

I did, however, notice something else. The surface of the cut was not perpendicular to the wall of the building. It went in at an angle. I frowned and squinted back behind me, trying to line it up with the wall of the building on the other side of the alley.

Murphy knew me well enough to see I’d noticed something, and I knew her well enough to see her sudden interest make furrows between her eyebrows as she forced herself to be quiet and let me work.

I got up and went to the far side of the alley. A light coating of snow and dust had coated the wall.

“Watch your eyes,” I murmured, squinting my own to slits. Then I raised my right hand, called up my will, and murmured, “Ventas reductas.”

The wind I called up wasn’t the usual burst I commonly used. It was far more toned-down than that, and it poured steadily from my outstretched hand. All the work I was doing with Molly had allowed me to rethink a lot of my basic evocations, the fast and dirty magic that wizards used in desperate and violent situations. I’d been trying to teach the spell to Molly, but she didn’t have the raw strength I had, and it would have practically knocked her unconscious to call up a heavy blast of air. I’d modified my teaching, just to get her comfortable with using a bit of air magic, and we’d accidentally developed a passable impersonation of an electric blow-dryer.

I used the dryer spell to gently brush away dust and snow from the wall. It took me about a minute and a half, and when I was finished I caught another scent under the brimstone stench and said, “Double crap.”

Murphy stepped forward with her flashlight and shone it on the wall.

The sigil had been painted on the wall in something thick and brown that smelled like blood. At first I thought it was a pentacle, but I saw the differences immediately.

“Harry,” Murphy said quietly. “Is it human?”

“Most likely,” I said. “Mortal blood is the strongest ink you can use for symbols like this in high-energy spells. I don’t think anything else could have contained the amounts of energy it would have taken to blow up this building.”

“It’s a pentacle, right?” Murphy asked. “Like the one you wear.”

I shook my head. “Different.”

“How so?” Her mouth twitched at one corner. “Other than the blood, I mean.”